The now-existing inter-system handover and reselection in a 2/3G dual-mode terminal is realized by the network controlling the threshold and the terminal reporting the level of measured signal. Different parameters are set up at the network terminal by telecommunications operators based on their individual requirements to control the operation of the terminal. However, nowadays in a highly competitive market, some of the operators only run 3G networks, while some others only run 2G networks. The networks are communicated by internet protocol. According to the current solution, the handover of the terminal is controlled by the network terminal. For those operators who rent networks from other operators, it's impossible for them to take part in the set up of the network parameters set up by the provider. At the same time, they wish to retain the terminal on their network to the greatest extent to reduce cost.
The current 2G-3G cell reselection method is realized by the network issuing a 3G neighbor cell list to the mobile terminal through system messages such as 2quarter/2ter or 5quarter/5ter when the 2G cell has a 3G neighbor cell. The terminal reports the level and quality of the 3G neighbor cell through a measurement report. The system message 2quarter/2ter is the supplement to the system messages 2, and the 3G neighbor cell list is issued through 2quarter/2ter. The criteria for 2G-3G inter-system reselection are:
1). The measured received signal code power (RSCP) of the 3G neighbor cell is greater than the power level strength of the serving cell and the received levels of all other non-serving cells by the frequency division duplex cell reselection offset (FDD_Qoffset, which denotes the inter-system cell reselection offset). That is, RSCP (Received Signal Code Power)>RLA (Received Level Average, the average received level of the cell)+FDD_Qoffset (inter-system cell reselection offset),
where the cell reselection offset is a parameter broadcast by the network.
2). The measured Ec/No of the 3G neighbor cell (Ec/No=RSCP/RSSI, that is the received signal code power received from the cell unit dBm/the total power received at the point (including the cell) unit dBm)≧FDD_Qmin (the minimum threshold value for Ec/No for inter-system cell reselection) and RSCP≧FDD_RSCP_threshold (the minimum threshold value for RSCP for inter-system cell reselection).
3). The above-mentioned criteria must be satisfied and last for 5 seconds.
In the above-mentioned criteria, except for the RSCP and the Ec/No of the 3G neighbor cell measured by the terminal, all other parameters are controlled by the network. The 2G-3G handover operates similarly.
According to the prior art, the development of GSM network is more mature and the GSM network coverage is very vast. Since some of the operators only run 3G networks, they wish that the terminal preferentially resides on the 3G networks to the greatest extent when GSM network and 3G network co-exist. However, because they do not own 2G networks, they cannot set up the network to optimize the network so that the terminal is not allowed to make a priority selection of the networks.
It is therefore very important to make improvement and development on the prior art.